"I knew something was wrong," said Stigler's father, Allen Levi Stigler Sr., as he recalled the painful Sunday door knock from two men in uniform. "One of them says your son is deceased in Iraq, and you can't breathe, and something is so hot in your throat, you can't say nothing. You lose your air."

The Pentagon spokesman, Army Col. Rob Manning, says an Army artillery unit was firing on an Islamic State mortar position "when a mishap occurred." Manning says there is no indication that ISIS played a role in the deaths. He says he cannot provide other details because the incident is under investigation.

Five others suffered injuries that Manning says are not life-threatening.

"The U.S. Armed Forces is great. A lot of good things can happen to you," Allen Stigler Sr. said. "But there's also danger."

Faces of the Fallen

The Stiglers say not knowing what happened to their son is the hardest part.

"He was coming home," said stepmother Leslie Stigler, through tears.

The soldier was on his first combat deployment and was expected home in a month.

"He will be missed terribly," Leslie Stigler said.

Stigler was posthumously promoted from specialist to sergeant. He was posthumously awarded the Bronze Star, Purple Heart, Meritorious Service Medal and Combat Action Badge. His funeral is planned for Saturday, Aug. 26, at 11 a.m. at Mount Olive Baptist Church in Arlington.